A multi-threaded large scale computer system, such as a database management system (“DBMS”), supports a number of different users concurrently. In a multi-threaded computer system there is only one execution of the software; that is, only one process. From the one process, a user thread is created for each user. All the user threads share the same process memory space, because they are part of the same process.
A cache is a storage area operating between a processor and another, slower storage area (such as a disk). Although, other schemes may exist, typical cache memory is evenly divided into a fixed number of finitely sized cache memory blocks, called a page. The cached data includes pages which have stored therein currently executing instructions and currently referenced data. The page stored in each cache memory block is typically controlled and managed through control blocks, there being a correspondence between a control block and a cache memory block. If a user thread references an instruction or data not in memory; then a page fault occurs, which causes the relevant page to be read from disk into the cache. Such an arrangement is typical of cache memory. Problems occur when more pages need to be cached than there are available cache blocks in the cache requiring reclamation of pages.